This invention relates to a structure for maintaining the integrity of a fire, vapor and smoke barrier which must have penetrations for present or future electrical cables, pipes, conduits or other purposes. Various types of fittings have been developed for providing smoke and vapor barriers. A typical fitting of this nature is disclosed in U.S. Pat. No. 3,655,907 issued to Robert A. Philibert et al on Apr. 11, 1972, and which is owned by the same corporation to which the present invention is assigned. The Philibert et al patent employs a sealing material, such as an elastomeric material which, under the force of pressure, deforms or distorts to seal an opening against the passage of smoke, gas or vapor. However, when such a fitting is exposed to intense heat, or direct flame, for a sufficient length of time, the sealing material is destroyed and smoke or vapor may pass through the barrier. With the integrity of the barrier broken, a fire or dangerous gas on one side may be transmitted to the other side.
There are numerous situations wherein safety considerations require maintaining the integrity of a barrier. For example, a high integrity barrier is required in locations such as; nuclear power plants, on ships, submarines, aircraft, space vehicles and many other more routine applications such as, walls, floors, ceilings, etc. to secure safety of personnel and/or equipment.
It has been suggested that the sealing material of the Philibert et al patent might degenerate in the presence of intense heat or flame. Even if this did not occur, the insulation on the wire passing through the sealing material might degenerate, shrink or burn in the presence of intense heat or flame. If this should occur, the integrity of the barrier would be destroyed just as effectively as if the sealing material had itself been destroyed.
Prior art devices have attempted to use an intumescent material to overcome the last named difficulty. An intumescent material is one which expands under certain conditions. The type of intumescent material which would find usefulness for the problem under consideration is one which will expand in the presence of heat or flame. U.S. Pat. No. 3,864,883 discloses the use of an intumescent material to provide some protection under certain circumstances.